It gets much more complicated than this, but it's basically because computer architecture is always based on multiples of two.
This is the reason why, as computers have got more powerful, memory amounts have gone from 32k (Dragon) to 64k (C64) 128k (Spectrum) etc. and more recently have done the same thing with Mb instead.
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but it's basically because computer architecture is always based on multiples of two.
multiples of 8. ( starting with 1byte = 8 bits )
although nowadays, when a manufacturer says their hard disk is 160 megabytes, they may actually mean 160,000,000 bytes.
see personal-computer-tutor.com/abc3/v30/vic30.htm
A common marketing ploy by hard drive manufacturers is to calculate the size of a hard disk by using the decimal 10 system of 1000 bytes = one kilobyte, instead of the binary system where 1024 bytes = one kilobyte (your PC only knows binary). This rounding off practice means you end up with a hard drive with a capacity less than what is indicated on the label. For example, a true 80 GB hard disk can hold 85,899,345,920 bytes, but by using the base 10 formula, 80 GB comes out to only 80,000,000,000 bytes Do the simple subtraction, that's 5,899,345,920 bytes less than the true value. Now calculate what 5,899,345,920 bytes converts to by entering 5899345920 in the Byte box above. You will find that it translates to a loss of 5.49419 GIGABYTES!
To perform the calculation manually:
True Size: 80 x 1024 X 1024 x 1024 = 85,899,345,920 bytes
False Size: 80 x 1000 x 1000 x 1000= 80,000,000,000 bytes
And there you have the reason for the size discrepancy when you correctly install a hard drive in Windows and its Properties report it to be smaller than what you thought. A PC only understands binary, 0's and 1's, and that's how Windows calculates your hard drive size. This means that an 80 GB drive, figured using the decimal 10 system, would only show as about 74.5GBs in Windows. A 40 GB drive would only show as about 37.2 GB The difference works out to about 7% less .....
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So that's what it's all about! The prefix K does not mean the same as the prefix k. I wonder how many people know that in this day and age of sloppy spelling? Not many I'll wager!
--
L\'escargot.
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The answer to the OP's question is simplle computers work in binary.
So that's what it's all about! The prefix K does not mean the same as the prefix k. I wonder how many people know that in this day and age of sloppy spelling? Not many I'll wager! -- L\'escargot.
>>
kb = kilobit
Kb = kilobyte (8kb)
mb = megabit (1000 kb)
Mb = megabyte (8 mb)
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>> but it's basically because computer architecture is always based on multiples of two. multiples of 8. ( starting with 1byte = 8 bits )
Hmmm.
I see the point you're making, but for the purposes of answering the original question it works on multiples of two. As comfirmed by your own quoted link - computers work on a binary system.
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It's a little unfair to claim it's a marketing ploy. In reality, the hard drive manufacturers (and broadband providers for that matter) have it right.
1KB = 1000 bytes, 1MB = 1000 KB, 1GB = 1000 MB
That is the correct SI usage (internationally agreed system of measurements) of the terms, the base 2 stuff came later on (by sloppy computer professionals), and is strictly inaccurate. The correct term for 1024 bytes is now defined as kibibyte or KiB, which, of course 99% of people have never heard of.
See:
en.wikipedia.org/wiki/Kilobyte
Therefore, although perhaps misleading, the hard drive manufacturers are in fact using the proper SI definitions of the terms kilobytes, megabyte and gigabyte. i.e. 10 to the power of X, rather than the slang usage from IT of 2 to the power of X.
To think of it another way, the vast majority of computers are indeed designed around base 2 (but not always), so 1024 bytes almost makes sense to be called a kilobyte (but should have used a separate term from the start), but hard drives and broadband capacity are not tied to base 2 in operation and so the base 10 numbers make more sense in that context anyway.
Confusing? Very!! ;-) I remember my IT lecturers in the early nineties getting confused too!! :0)
OTOH, I've never seen hard drive manufacturers or broadband operators go out of their way to clear up this almost universal misunderstanding...
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Here's another page which explains the situation well, and why Windows is, in fact, reporting the wrong value and has been officially since 1998 when the new system was agreed:
tinyurl.com/ycvbwh
I guess Microsoft feel they're above mere international standards? :)
This is why when people say IT "professional", the second word has ironic quotes around it...
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Windows is, in fact, reporting the wrong value and has been officially since 1998 when the new system was agreed:>>
Windows will report, for instance 1024Mb of RAM rather than 1000Mb though will round it to 1Gb rather than 1.024Gb thus providing a correction in the rounding.
Kib, Mib and Gib in theory provide greater accuracy though they simply serve to deliver further confusion.
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Hmmm. I see the point you're making, but for the purposes of answering the original question it works on multiples of two
in reply to bazzabear: so why is is 1024, and not 1026 or 1022? (try dividing by 8 and that should be clear) .
kb = kilobit, Kb = kilobyte (8kb), mb = megabit (1000 kb), Mb = megabyte (8 mb)
in reply to cheddar: i think you will find that bits and bytes are differentiated by the use of lower and upper case letter "b".
It's a little unfair to claim it's a marketing ploy.
in reply to theoilburner - the quote re. marketing ploy was from the link, and not my view. i have not done any research on this but i believe ( i may be wrong) that some manufacturers did use to quote the capacity in bytes to make it clear what units they were using. now that there are fewer and fewer competitors, i do not know if anyof the defunct ones were those who quoted the "real" size in bytes.
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>> Hmmm. I see the point you're making, but for the purposes of answering the original question it works on >> multiples of two in reply to bazzabear: so why is is 1024, and not 1026 or 1022? (try dividing by 8 and that should be clear) .
Because I didn't explain myself very well: When I said multiples, I meant as in 2x2, 2x2x2, 2x2x2x2 etc., not 2x1, 2x2, 2x3, 2x4. In other words it is powers of 2, but I was trying to make it as simple as possible, and made my wording ambiguous.
This doesn't make you right about multiples of eight. Using your own argument against you, why is it not 1032 or 1040?
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Using your own argument against you
in reply to bazzabear, i accept you meant to say powers of 2 rather than multiples of 2.
re. your comment in the first reply:As comfirmed by your own quoted link - computers work on a binary system. >>
i may be talking at cross-purposes. the factor of 8 i was referring to was in relation to the use of kilo, mega, etc.
as i said in my first post, 1 byte = 8 bits. as you say computers use a binary suystem. which comes from the binary digit (bit) represented by on-off state.
factor of 8 (or 2 raised to power 3) is common in all the kilo, mega, giga, tera, etc. multiples as is demonstrated in the table towards the bottom of the page linked by stuartli:
www.t1shopper.com/tools/calculate/
i hope that clears up what i meant to say. but still probably not very well explained :: ;-) ::
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:)
I think we were talking about slightly different ways of looking at it. Looking at the rest of what you've written, I certainly think you know more about this area than I do!
Unfortunately I spent most of my computer architecture lectures uncontrollably sniggering at the lecturer saying '32' in a broad Irish accent.
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in reply to cheddar: i think you will find that bits and bytes are differentiated by the use of lower and upper case letter "b".
Yes of course you are right i mIXed my caSEs, so:
Kb = kilobit
KB = kilobyte (8Kb)
Mb = megabit (1000 Kb),
etc
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.... the hard drive manufacturers (and broadband providers for that matter) have it right. 1KB = 1000 bytes, 1MB = 1000 KB, 1GB = 1000 MB
My ISP allows me 2GB per month. Doesn't that imply that they they use 1GB = 1024 MB?
--
L\'escargot.
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Check the small print; they'll probably say 1GB = 1000 MB = 1000 KB, mine does (Plus.net)
So you thought you were getting 2,147,483,648 bytes per month, when in fact you'll get 2,000,000,000 bytes, for what it's worth! :)
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It just goes to prove that that are 10 types of people in the world. Those who understand binary and those who don't.
JH
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Add another: those who do and don't care:-)
madf
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"Add another: those who do and don't care:-)"
Not forgetting those who don't and don't care
--
Phil
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"Add another: those who do and don't care:-)" Not forgetting those who don't and don't care -- Phil
So that's 100 types of people then.
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>>My ISP allows me 2GB per month. Doesn't that imply that they they use 1GB = 1024 MB?>>
My bandwidth meter reads 1GB as 1000MB etc as does a download manager.
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My Tautology Bandwidth Meter (as recommended by your good self) can be set (as I've no doubt you know!) for 1KB to be either 1024 Bytes or 1000 Bytes. Are you saying it should be set to 1000 Bytes?
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L\'escargot.
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>>can be set (as I've no doubt you know!) >>
Oops! Forgot about that. In fact when I originally installed Tautology Bandwidth Meter I was on a 2GB a month limit, so set it at 1024 as a safety margin - it's still on that setting some 20 months later...:-)
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